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Thread: Algae Issue - Pool won't hold Chlorine Levels

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    Algae Issue - Pool won't hold Chlorine Levels

    Howdy! New to pool forum, fourth year of owning a pool. I am experiencing new issues this year with respect to algae and ability of my pool water to respond to chlorine.

    For example, I scrubbed algae from the walls on Sunday, shocked the pool using ChlorBrite fine powder, added a puck to the skimmer basket, ran the pump for 24 hours from Sunday to Monday and another 12 hours today. Here are my water test results from earlier this evening:
    FC - 0 ppm
    TC - 0 ppm
    Combined CL - 0 ppm
    pH - 7.4
    Hardness - 180 ppm
    CYA - 90 ppm
    Alkalinity - 75 ppm
    Phosphates - 800 ppb

    I back washed my DE filter, replaced DE, and added PhosFree to reduce Phosphates as that is what the pool store said was causing my chlorine issues.

    Help!
    --
    13,500 gallon -IG - plaster - DE Filter (48 sq ft) - 2 HP Hayward Super II Pump

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    Butterfly's Avatar
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    Re: Algae Issue - Pool won't hold Chlorine Levels

    Welcome to the forum

    Two problems: 1. No chlorine and 2. CYA too high

    I suggest you dump about half the water and get the CYA down to about 50. Then follow the Shock Process up in Pool School.

    Phosphates, well, just forget about them and don't waste your $ buying removers.
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

    ~ One should not use a sledge hammer to swat a mosquito. ~

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    Butterfly's Avatar
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    Re: Algae Issue - Pool won't hold Chlorine Levels

    btw, here's some info on brushes for different types of pools:

    Nylon is for vinyl, fiberglass, tile, and plaster that is less than one year. (Plaster includes any exposed aggregate and marcite finish, btw!) Combo brushes are for older plaster. All stainless are for algae (very stubborn green algae and also the ONLY brush for black algae.)

    You CAN unscrew the Wall Whale from the nylon brush it comes with and screw it on a combo brush if your plaster is over a year old. Newer plaster is really too soft for anyting other than a nylon brush.
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

    ~ One should not use a sledge hammer to swat a mosquito. ~

    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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    Re: Algae Issue - Pool won't hold Chlorine Levels

    Quote Originally Posted by Butterfly
    Welcome to the forum

    Two problems: 1. No chlorine and 2. CYA too high.
    Thanks! Quick question though. I thought that high levels of CYA would show normal levels of chlorine but that it would be ineffective - especially right after shock / chlorine addition to the pool?

    I need to buy a proper water tester. The two pool places near me return wildly different CYA results. My readings above are from the place that reports high. The other place reports a CYA of about 60 - 65.
    --
    13,500 gallon -IG - plaster - DE Filter (48 sq ft) - 2 HP Hayward Super II Pump

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    Butterfly's Avatar
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    Re: Algae Issue - Pool won't hold Chlorine Levels

    Yep, you need to invest in one of the recommended test kits. The TF100 is the fav around here. Link in my sig. You might also want to get the speed stir. Lotsa help and fun!

    I'm not sure I understand the question about the chlorine. Do some reading up in Pool School and get back to us on that.

    The ChlorBrite is Dichlor and it adds CYA along w/the chlorine! No more powders!

    The Chlorine/CYA ratio is found in Pool School. Here's a link:
    pool-school/chlorine_cya_chart_shock

    Since you have two CYA tests and you think one is high, let's split the difference and call it 75. Or maybe 90 really is closer to correct. (You really neeed a test kit!)

    With a CYA of 75ish , you will need to maintain normal FC levels between 6 to 11, and never below 6. That is your maintenance normal FC range.

    However, you had/have zero FC and algae and need to follow the Shock Process in Pool School.

    It is best to use bleach/liquid chlorine. Find the best deal in town and stock up. Here's a link to the Shock Process: pool-school/shocking_your_pool

    Have you ordered the test kit yet?
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

    ~ One should not use a sledge hammer to swat a mosquito. ~

    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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